content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import hu.akarnokd.reactivestreams.extensions.RelaxedSubscriber;
  import io.reactivex.flowable.Flowable;
  import io.reactivex.flowable.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.flowable.internal.utils.BackpressureHelper;
  
  public final class FlowableOnBackpressureLatest<T> extends AbstractFlowableWithUpstream<T, T> {
  
      public FlowableOnBackpressureLatest(Flowable<T> source) {
          super(source);
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          source.subscribe(new BackpressureLatestSubscriber<T>(s));
      }
  
      static final class BackpressureLatestSubscriber<T> extends AtomicInteger implements RelaxedSubscriber<T>, Subscription {
  
          private static final long serialVersionUID = 163080509307634843L;
  
          final Subscriber<? super T> actual;
  
          Subscription s;
  
          volatile boolean done;
          Throwable error;
  
          volatile boolean cancelled;
  
          final AtomicLong requested = new AtomicLong();
  
          final AtomicReference<T> current = new AtomicReference<T>();
  
          BackpressureLatestSubscriber(Subscriber<? super T> actual) {
              this.actual = actual;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.s, s)) {
                  this.s = s;
                  actual.onSubscribe(this);
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(T t) {
              current.lazySet(t);
              drain();
          }
  
          @Override
          public void onError(Throwable t) {
              error = t;
              done = true;
              drain();
          }
  
          @Override
          public void onComplete() {
              done = true;
              drain();
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
                  drain();
              }
          }
  
          @Override
          public void cancel() {
              if (!cancelled) {
                  cancelled = true;
                  s.cancel();
  
                  if (getAndIncrement() == 0) {
                      current.lazySet(null);
                  }
              }
          }
  
          void drain() {
              if (getAndIncrement() != 0) {
                  return;
              }
              final Subscriber<? super T> a = actual;
              int missed = 1;
              final AtomicLong r = requested;
              final AtomicReference<T> q = current;
  
              for (;;) {
                  long e = 0L;
  
                  while (e != r.get()) {
                      boolean d = done;
                      T v = q.getAndSet(null);
                      boolean empty = v == null;
  
                      if (checkTerminated(d, empty, a, q)) {
                          return;
                      }
  
                      if (empty) {
                          break;
                      }
  
                      a.onNext(v);
  
                      e++;
                  }
  
                  if (e == r.get() && checkTerminated(done, q.get() == null, a, q)) {
                      return;
                  }
  
                  if (e != 0L) {
                      BackpressureHelper.produced(r, e);
                  }
  
                  missed = addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
              }
          }
  
          boolean checkTerminated(boolean d, boolean empty, Subscriber<?> a, AtomicReference<T> q) {
              if (cancelled) {
                  q.lazySet(null);
                  return true;
              }
  
              if (d) {
                  Throwable e = error;
                  if (e != null) {
                      q.lazySet(null);
                      a.onError(e);
                      return true;
                  } else
                  if (empty) {
                      a.onComplete();
                      return true;
                  }
              }
  
              return false;
          }
      }
  }
  